intermediate changes

ref:cde9a383711a11544ce7e107a78147fb96cc4029

1 files changed, 1105 insertions, 0 deletions

diff --git a/contrib/libs/llvm12/include/llvm/CodeGen/MachineBasicBlock.h b/contrib/libs/llvm12/include/llvm/CodeGen/MachineBasicBlock.h
new file mode 100644
index 00000000000..fb36c30de81
--- /dev/null
+++ b/contrib/libs/llvm12/include/llvm/CodeGen/MachineBasicBlock.h
@@ -0,0 +1,1105 @@
+#pragma once
+
+#ifdef __GNUC__
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-parameter"
+#endif
+
+//===- llvm/CodeGen/MachineBasicBlock.h -------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Collect the sequence of machine instructions for a basic block.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_MACHINEBASICBLOCK_H
+#define LLVM_CODEGEN_MACHINEBASICBLOCK_H
+
+#include "llvm/ADT/GraphTraits.h"
+#include "llvm/ADT/ilist.h"
+#include "llvm/ADT/iterator_range.h"
+#include "llvm/ADT/SparseBitVector.h"
+#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/MachineInstrBundleIterator.h"
+#include "llvm/IR/DebugLoc.h"
+#include "llvm/MC/LaneBitmask.h"
+#include "llvm/Support/BranchProbability.h"
+#include <cassert>
+#include <cstdint>
+#include <functional>
+#include <iterator>
+#include <string>
+#include <vector>
+
+namespace llvm {
+
+class BasicBlock;
+class MachineFunction;
+class MCSymbol;
+class ModuleSlotTracker;
+class Pass;
+class Printable;
+class SlotIndexes;
+class StringRef;
+class raw_ostream;
+class LiveIntervals;
+class TargetRegisterClass;
+class TargetRegisterInfo;
+
+// This structure uniquely identifies a basic block section.
+// Possible values are
+//  {Type: Default, Number: (unsigned)} (These are regular section IDs)
+//  {Type: Exception, Number: 0}  (ExceptionSectionID)
+//  {Type: Cold, Number: 0}  (ColdSectionID)
+struct MBBSectionID {
+  enum SectionType {
+    Default = 0, // Regular section (these sections are distinguished by the
+                 // Number field).
+    Exception,   // Special section type for exception handling blocks
+    Cold,        // Special section type for cold blocks
+  } Type;
+  unsigned Number;
+
+  MBBSectionID(unsigned N) : Type(Default), Number(N) {}
+
+  // Special unique sections for cold and exception blocks.
+  const static MBBSectionID ColdSectionID;
+  const static MBBSectionID ExceptionSectionID;
+
+  bool operator==(const MBBSectionID &Other) const {
+    return Type == Other.Type && Number == Other.Number;
+  }
+
+  bool operator!=(const MBBSectionID &Other) const { return !(*this == Other); }
+
+private:
+  // This is only used to construct the special cold and exception sections.
+  MBBSectionID(SectionType T) : Type(T), Number(0) {}
+};
+
+template <> struct ilist_traits<MachineInstr> {
+private:
+  friend class MachineBasicBlock; // Set by the owning MachineBasicBlock.
+
+  MachineBasicBlock *Parent;
+
+  using instr_iterator =
+      simple_ilist<MachineInstr, ilist_sentinel_tracking<true>>::iterator;
+
+public:
+  void addNodeToList(MachineInstr *N);
+  void removeNodeFromList(MachineInstr *N);
+  void transferNodesFromList(ilist_traits &FromList, instr_iterator First,
+                             instr_iterator Last);
+  void deleteNode(MachineInstr *MI);
+};
+
+class MachineBasicBlock
+    : public ilist_node_with_parent<MachineBasicBlock, MachineFunction> {
+public:
+  /// Pair of physical register and lane mask.
+  /// This is not simply a std::pair typedef because the members should be named
+  /// clearly as they both have an integer type.
+  struct RegisterMaskPair {
+  public:
+    MCPhysReg PhysReg;
+    LaneBitmask LaneMask;
+
+    RegisterMaskPair(MCPhysReg PhysReg, LaneBitmask LaneMask)
+        : PhysReg(PhysReg), LaneMask(LaneMask) {}
+  };
+
+private:
+  using Instructions = ilist<MachineInstr, ilist_sentinel_tracking<true>>;
+
+  Instructions Insts;
+  const BasicBlock *BB;
+  int Number;
+  MachineFunction *xParent;
+
+  /// Keep track of the predecessor / successor basic blocks.
+  std::vector<MachineBasicBlock *> Predecessors;
+  std::vector<MachineBasicBlock *> Successors;
+
+  /// Keep track of the probabilities to the successors. This vector has the
+  /// same order as Successors, or it is empty if we don't use it (disable
+  /// optimization).
+  std::vector<BranchProbability> Probs;
+  using probability_iterator = std::vector<BranchProbability>::iterator;
+  using const_probability_iterator =
+      std::vector<BranchProbability>::const_iterator;
+
+  Optional<uint64_t> IrrLoopHeaderWeight;
+
+  /// Keep track of the physical registers that are livein of the basicblock.
+  using LiveInVector = std::vector<RegisterMaskPair>;
+  LiveInVector LiveIns;
+
+  /// Alignment of the basic block. One if the basic block does not need to be
+  /// aligned.
+  Align Alignment;
+
+  /// Indicate that this basic block is entered via an exception handler.
+  bool IsEHPad = false;
+
+  /// Indicate that this basic block is potentially the target of an indirect
+  /// branch.
+  bool AddressTaken = false;
+
+  /// Indicate that this basic block needs its symbol be emitted regardless of
+  /// whether the flow just falls-through to it.
+  bool LabelMustBeEmitted = false;
+
+  /// Indicate that this basic block is the entry block of an EH scope, i.e.,
+  /// the block that used to have a catchpad or cleanuppad instruction in the
+  /// LLVM IR.
+  bool IsEHScopeEntry = false;
+
+  /// Indicate that this basic block is the entry block of an EH funclet.
+  bool IsEHFuncletEntry = false;
+
+  /// Indicate that this basic block is the entry block of a cleanup funclet.
+  bool IsCleanupFuncletEntry = false;
+
+  /// With basic block sections, this stores the Section ID of the basic block.
+  MBBSectionID SectionID{0};
+
+  // Indicate that this basic block begins a section.
+  bool IsBeginSection = false;
+
+  // Indicate that this basic block ends a section.
+  bool IsEndSection = false;
+
+  /// Indicate that this basic block is the indirect dest of an INLINEASM_BR.
+  bool IsInlineAsmBrIndirectTarget = false;
+
+  /// since getSymbol is a relatively heavy-weight operation, the symbol
+  /// is only computed once and is cached.
+  mutable MCSymbol *CachedMCSymbol = nullptr;
+
+  /// Marks the end of the basic block. Used during basic block sections to
+  /// calculate the size of the basic block, or the BB section ending with it.
+  mutable MCSymbol *CachedEndMCSymbol = nullptr;
+
+  // Intrusive list support
+  MachineBasicBlock() = default;
+
+  explicit MachineBasicBlock(MachineFunction &MF, const BasicBlock *BB);
+
+  ~MachineBasicBlock();
+
+  // MachineBasicBlocks are allocated and owned by MachineFunction.
+  friend class MachineFunction;
+
+public:
+  /// Return the LLVM basic block that this instance corresponded to originally.
+  /// Note that this may be NULL if this instance does not correspond directly
+  /// to an LLVM basic block.
+  const BasicBlock *getBasicBlock() const { return BB; }
+
+  /// Return the name of the corresponding LLVM basic block, or an empty string.
+  StringRef getName() const;
+
+  /// Return a formatted string to identify this block and its parent function.
+  std::string getFullName() const;
+
+  /// Test whether this block is potentially the target of an indirect branch.
+  bool hasAddressTaken() const { return AddressTaken; }
+
+  /// Set this block to reflect that it potentially is the target of an indirect
+  /// branch.
+  void setHasAddressTaken() { AddressTaken = true; }
+
+  /// Test whether this block must have its label emitted.
+  bool hasLabelMustBeEmitted() const { return LabelMustBeEmitted; }
+
+  /// Set this block to reflect that, regardless how we flow to it, we need
+  /// its label be emitted.
+  void setLabelMustBeEmitted() { LabelMustBeEmitted = true; }
+
+  /// Return the MachineFunction containing this basic block.
+  const MachineFunction *getParent() const { return xParent; }
+  MachineFunction *getParent() { return xParent; }
+
+  using instr_iterator = Instructions::iterator;
+  using const_instr_iterator = Instructions::const_iterator;
+  using reverse_instr_iterator = Instructions::reverse_iterator;
+  using const_reverse_instr_iterator = Instructions::const_reverse_iterator;
+
+  using iterator = MachineInstrBundleIterator<MachineInstr>;
+  using const_iterator = MachineInstrBundleIterator<const MachineInstr>;
+  using reverse_iterator = MachineInstrBundleIterator<MachineInstr, true>;
+  using const_reverse_iterator =
+      MachineInstrBundleIterator<const MachineInstr, true>;
+
+  unsigned size() const { return (unsigned)Insts.size(); }
+  bool empty() const { return Insts.empty(); }
+
+  MachineInstr       &instr_front()       { return Insts.front(); }
+  MachineInstr       &instr_back()        { return Insts.back();  }
+  const MachineInstr &instr_front() const { return Insts.front(); }
+  const MachineInstr &instr_back()  const { return Insts.back();  }
+
+  MachineInstr       &front()             { return Insts.front(); }
+  MachineInstr       &back()              { return *--end();      }
+  const MachineInstr &front()       const { return Insts.front(); }
+  const MachineInstr &back()        const { return *--end();      }
+
+  instr_iterator                instr_begin()       { return Insts.begin();  }
+  const_instr_iterator          instr_begin() const { return Insts.begin();  }
+  instr_iterator                  instr_end()       { return Insts.end();    }
+  const_instr_iterator            instr_end() const { return Insts.end();    }
+  reverse_instr_iterator       instr_rbegin()       { return Insts.rbegin(); }
+  const_reverse_instr_iterator instr_rbegin() const { return Insts.rbegin(); }
+  reverse_instr_iterator       instr_rend  ()       { return Insts.rend();   }
+  const_reverse_instr_iterator instr_rend  () const { return Insts.rend();   }
+
+  using instr_range = iterator_range<instr_iterator>;
+  using const_instr_range = iterator_range<const_instr_iterator>;
+  instr_range instrs() { return instr_range(instr_begin(), instr_end()); }
+  const_instr_range instrs() const {
+    return const_instr_range(instr_begin(), instr_end());
+  }
+
+  iterator                begin()       { return instr_begin();  }
+  const_iterator          begin() const { return instr_begin();  }
+  iterator                end  ()       { return instr_end();    }
+  const_iterator          end  () const { return instr_end();    }
+  reverse_iterator rbegin() {
+    return reverse_iterator::getAtBundleBegin(instr_rbegin());
+  }
+  const_reverse_iterator rbegin() const {
+    return const_reverse_iterator::getAtBundleBegin(instr_rbegin());
+  }
+  reverse_iterator rend() { return reverse_iterator(instr_rend()); }
+  const_reverse_iterator rend() const {
+    return const_reverse_iterator(instr_rend());
+  }
+
+  /// Support for MachineInstr::getNextNode().
+  static Instructions MachineBasicBlock::*getSublistAccess(MachineInstr *) {
+    return &MachineBasicBlock::Insts;
+  }
+
+  inline iterator_range<iterator> terminators() {
+    return make_range(getFirstTerminator(), end());
+  }
+  inline iterator_range<const_iterator> terminators() const {
+    return make_range(getFirstTerminator(), end());
+  }
+
+  /// Returns a range that iterates over the phis in the basic block.
+  inline iterator_range<iterator> phis() {
+    return make_range(begin(), getFirstNonPHI());
+  }
+  inline iterator_range<const_iterator> phis() const {
+    return const_cast<MachineBasicBlock *>(this)->phis();
+  }
+
+  // Machine-CFG iterators
+  using pred_iterator = std::vector<MachineBasicBlock *>::iterator;
+  using const_pred_iterator = std::vector<MachineBasicBlock *>::const_iterator;
+  using succ_iterator = std::vector<MachineBasicBlock *>::iterator;
+  using const_succ_iterator = std::vector<MachineBasicBlock *>::const_iterator;
+  using pred_reverse_iterator =
+      std::vector<MachineBasicBlock *>::reverse_iterator;
+  using const_pred_reverse_iterator =
+      std::vector<MachineBasicBlock *>::const_reverse_iterator;
+  using succ_reverse_iterator =
+      std::vector<MachineBasicBlock *>::reverse_iterator;
+  using const_succ_reverse_iterator =
+      std::vector<MachineBasicBlock *>::const_reverse_iterator;
+  pred_iterator        pred_begin()       { return Predecessors.begin(); }
+  const_pred_iterator  pred_begin() const { return Predecessors.begin(); }
+  pred_iterator        pred_end()         { return Predecessors.end();   }
+  const_pred_iterator  pred_end()   const { return Predecessors.end();   }
+  pred_reverse_iterator        pred_rbegin()
+                                          { return Predecessors.rbegin();}
+  const_pred_reverse_iterator  pred_rbegin() const
+                                          { return Predecessors.rbegin();}
+  pred_reverse_iterator        pred_rend()
+                                          { return Predecessors.rend();  }
+  const_pred_reverse_iterator  pred_rend()   const
+                                          { return Predecessors.rend();  }
+  unsigned             pred_size()  const {
+    return (unsigned)Predecessors.size();
+  }
+  bool                 pred_empty() const { return Predecessors.empty(); }
+  succ_iterator        succ_begin()       { return Successors.begin();   }
+  const_succ_iterator  succ_begin() const { return Successors.begin();   }
+  succ_iterator        succ_end()         { return Successors.end();     }
+  const_succ_iterator  succ_end()   const { return Successors.end();     }
+  succ_reverse_iterator        succ_rbegin()
+                                          { return Successors.rbegin();  }
+  const_succ_reverse_iterator  succ_rbegin() const
+                                          { return Successors.rbegin();  }
+  succ_reverse_iterator        succ_rend()
+                                          { return Successors.rend();    }
+  const_succ_reverse_iterator  succ_rend()   const
+                                          { return Successors.rend();    }
+  unsigned             succ_size()  const {
+    return (unsigned)Successors.size();
+  }
+  bool                 succ_empty() const { return Successors.empty();   }
+
+  inline iterator_range<pred_iterator> predecessors() {
+    return make_range(pred_begin(), pred_end());
+  }
+  inline iterator_range<const_pred_iterator> predecessors() const {
+    return make_range(pred_begin(), pred_end());
+  }
+  inline iterator_range<succ_iterator> successors() {
+    return make_range(succ_begin(), succ_end());
+  }
+  inline iterator_range<const_succ_iterator> successors() const {
+    return make_range(succ_begin(), succ_end());
+  }
+
+  // LiveIn management methods.
+
+  /// Adds the specified register as a live in. Note that it is an error to add
+  /// the same register to the same set more than once unless the intention is
+  /// to call sortUniqueLiveIns after all registers are added.
+  void addLiveIn(MCRegister PhysReg,
+                 LaneBitmask LaneMask = LaneBitmask::getAll()) {
+    LiveIns.push_back(RegisterMaskPair(PhysReg, LaneMask));
+  }
+  void addLiveIn(const RegisterMaskPair &RegMaskPair) {
+    LiveIns.push_back(RegMaskPair);
+  }
+
+  /// Sorts and uniques the LiveIns vector. It can be significantly faster to do
+  /// this than repeatedly calling isLiveIn before calling addLiveIn for every
+  /// LiveIn insertion.
+  void sortUniqueLiveIns();
+
+  /// Clear live in list.
+  void clearLiveIns();
+
+  /// Add PhysReg as live in to this block, and ensure that there is a copy of
+  /// PhysReg to a virtual register of class RC. Return the virtual register
+  /// that is a copy of the live in PhysReg.
+  Register addLiveIn(MCRegister PhysReg, const TargetRegisterClass *RC);
+
+  /// Remove the specified register from the live in set.
+  void removeLiveIn(MCPhysReg Reg,
+                    LaneBitmask LaneMask = LaneBitmask::getAll());
+
+  /// Return true if the specified register is in the live in set.
+  bool isLiveIn(MCPhysReg Reg,
+                LaneBitmask LaneMask = LaneBitmask::getAll()) const;
+
+  // Iteration support for live in sets.  These sets are kept in sorted
+  // order by their register number.
+  using livein_iterator = LiveInVector::const_iterator;
+#ifndef NDEBUG
+  /// Unlike livein_begin, this method does not check that the liveness
+  /// information is accurate. Still for debug purposes it may be useful
+  /// to have iterators that won't assert if the liveness information
+  /// is not current.
+  livein_iterator livein_begin_dbg() const { return LiveIns.begin(); }
+  iterator_range<livein_iterator> liveins_dbg() const {
+    return make_range(livein_begin_dbg(), livein_end());
+  }
+#endif
+  livein_iterator livein_begin() const;
+  livein_iterator livein_end()   const { return LiveIns.end(); }
+  bool            livein_empty() const { return LiveIns.empty(); }
+  iterator_range<livein_iterator> liveins() const {
+    return make_range(livein_begin(), livein_end());
+  }
+
+  /// Remove entry from the livein set and return iterator to the next.
+  livein_iterator removeLiveIn(livein_iterator I);
+
+  /// Get the clobber mask for the start of this basic block. Funclets use this
+  /// to prevent register allocation across funclet transitions.
+  const uint32_t *getBeginClobberMask(const TargetRegisterInfo *TRI) const;
+
+  /// Get the clobber mask for the end of the basic block.
+  /// \see getBeginClobberMask()
+  const uint32_t *getEndClobberMask(const TargetRegisterInfo *TRI) const;
+
+  /// Return alignment of the basic block.
+  Align getAlignment() const { return Alignment; }
+
+  /// Set alignment of the basic block.
+  void setAlignment(Align A) { Alignment = A; }
+
+  /// Returns true if the block is a landing pad. That is this basic block is
+  /// entered via an exception handler.
+  bool isEHPad() const { return IsEHPad; }
+
+  /// Indicates the block is a landing pad.  That is this basic block is entered
+  /// via an exception handler.
+  void setIsEHPad(bool V = true) { IsEHPad = V; }
+
+  bool hasEHPadSuccessor() const;
+
+  /// Returns true if this is the entry block of the function.
+  bool isEntryBlock() const;
+
+  /// Returns true if this is the entry block of an EH scope, i.e., the block
+  /// that used to have a catchpad or cleanuppad instruction in the LLVM IR.
+  bool isEHScopeEntry() const { return IsEHScopeEntry; }
+
+  /// Indicates if this is the entry block of an EH scope, i.e., the block that
+  /// that used to have a catchpad or cleanuppad instruction in the LLVM IR.
+  void setIsEHScopeEntry(bool V = true) { IsEHScopeEntry = V; }
+
+  /// Returns true if this is the entry block of an EH funclet.
+  bool isEHFuncletEntry() const { return IsEHFuncletEntry; }
+
+  /// Indicates if this is the entry block of an EH funclet.
+  void setIsEHFuncletEntry(bool V = true) { IsEHFuncletEntry = V; }
+
+  /// Returns true if this is the entry block of a cleanup funclet.
+  bool isCleanupFuncletEntry() const { return IsCleanupFuncletEntry; }
+
+  /// Indicates if this is the entry block of a cleanup funclet.
+  void setIsCleanupFuncletEntry(bool V = true) { IsCleanupFuncletEntry = V; }
+
+  /// Returns true if this block begins any section.
+  bool isBeginSection() const { return IsBeginSection; }
+
+  /// Returns true if this block ends any section.
+  bool isEndSection() const { return IsEndSection; }
+
+  void setIsBeginSection(bool V = true) { IsBeginSection = V; }
+
+  void setIsEndSection(bool V = true) { IsEndSection = V; }
+
+  /// Returns the section ID of this basic block.
+  MBBSectionID getSectionID() const { return SectionID; }
+
+  /// Returns the unique section ID number of this basic block.
+  unsigned getSectionIDNum() const {
+    return ((unsigned)MBBSectionID::SectionType::Cold) -
+           ((unsigned)SectionID.Type) + SectionID.Number;
+  }
+
+  /// Sets the section ID for this basic block.
+  void setSectionID(MBBSectionID V) { SectionID = V; }
+
+  /// Returns the MCSymbol marking the end of this basic block.
+  MCSymbol *getEndSymbol() const;
+
+  /// Returns true if this block may have an INLINEASM_BR (overestimate, by
+  /// checking if any of the successors are indirect targets of any inlineasm_br
+  /// in the function).
+  bool mayHaveInlineAsmBr() const;
+
+  /// Returns true if this is the indirect dest of an INLINEASM_BR.
+  bool isInlineAsmBrIndirectTarget() const {
+    return IsInlineAsmBrIndirectTarget;
+  }
+
+  /// Indicates if this is the indirect dest of an INLINEASM_BR.
+  void setIsInlineAsmBrIndirectTarget(bool V = true) {
+    IsInlineAsmBrIndirectTarget = V;
+  }
+
+  /// Returns true if it is legal to hoist instructions into this block.
+  bool isLegalToHoistInto() const;
+
+  // Code Layout methods.
+
+  /// Move 'this' block before or after the specified block.  This only moves
+  /// the block, it does not modify the CFG or adjust potential fall-throughs at
+  /// the end of the block.
+  void moveBefore(MachineBasicBlock *NewAfter);
+  void moveAfter(MachineBasicBlock *NewBefore);
+
+  /// Returns true if this and MBB belong to the same section.
+  bool sameSection(const MachineBasicBlock *MBB) const {
+    return getSectionID() == MBB->getSectionID();
+  }
+
+  /// Update the terminator instructions in block to account for changes to
+  /// block layout which may have been made. PreviousLayoutSuccessor should be
+  /// set to the block which may have been used as fallthrough before the block
+  /// layout was modified.  If the block previously fell through to that block,
+  /// it may now need a branch. If it previously branched to another block, it
+  /// may now be able to fallthrough to the current layout successor.
+  void updateTerminator(MachineBasicBlock *PreviousLayoutSuccessor);
+
+  // Machine-CFG mutators
+
+  /// Add Succ as a successor of this MachineBasicBlock.  The Predecessors list
+  /// of Succ is automatically updated. PROB parameter is stored in
+  /// Probabilities list. The default probability is set as unknown. Mixing
+  /// known and unknown probabilities in successor list is not allowed. When all
+  /// successors have unknown probabilities, 1 / N is returned as the
+  /// probability for each successor, where N is the number of successors.
+  ///
+  /// Note that duplicate Machine CFG edges are not allowed.
+  void addSuccessor(MachineBasicBlock *Succ,
+                    BranchProbability Prob = BranchProbability::getUnknown());
+
+  /// Add Succ as a successor of this MachineBasicBlock.  The Predecessors list
+  /// of Succ is automatically updated. The probability is not provided because
+  /// BPI is not available (e.g. -O0 is used), in which case edge probabilities
+  /// won't be used. Using this interface can save some space.
+  void addSuccessorWithoutProb(MachineBasicBlock *Succ);
+
+  /// Set successor probability of a given iterator.
+  void setSuccProbability(succ_iterator I, BranchProbability Prob);
+
+  /// Normalize probabilities of all successors so that the sum of them becomes
+  /// one. This is usually done when the current update on this MBB is done, and
+  /// the sum of its successors' probabilities is not guaranteed to be one. The
+  /// user is responsible for the correct use of this function.
+  /// MBB::removeSuccessor() has an option to do this automatically.
+  void normalizeSuccProbs() {
+    BranchProbability::normalizeProbabilities(Probs.begin(), Probs.end());
+  }
+
+  /// Validate successors' probabilities and check if the sum of them is
+  /// approximate one. This only works in DEBUG mode.
+  void validateSuccProbs() const;
+
+  /// Remove successor from the successors list of this MachineBasicBlock. The
+  /// Predecessors list of Succ is automatically updated.
+  /// If NormalizeSuccProbs is true, then normalize successors' probabilities
+  /// after the successor is removed.
+  void removeSuccessor(MachineBasicBlock *Succ,
+                       bool NormalizeSuccProbs = false);
+
+  /// Remove specified successor from the successors list of this
+  /// MachineBasicBlock. The Predecessors list of Succ is automatically updated.
+  /// If NormalizeSuccProbs is true, then normalize successors' probabilities
+  /// after the successor is removed.
+  /// Return the iterator to the element after the one removed.
+  succ_iterator removeSuccessor(succ_iterator I,
+                                bool NormalizeSuccProbs = false);
+
+  /// Replace successor OLD with NEW and update probability info.
+  void replaceSuccessor(MachineBasicBlock *Old, MachineBasicBlock *New);
+
+  /// Copy a successor (and any probability info) from original block to this
+  /// block's. Uses an iterator into the original blocks successors.
+  ///
+  /// This is useful when doing a partial clone of successors. Afterward, the
+  /// probabilities may need to be normalized.
+  void copySuccessor(MachineBasicBlock *Orig, succ_iterator I);
+
+  /// Split the old successor into old plus new and updates the probability
+  /// info.
+  void splitSuccessor(MachineBasicBlock *Old, MachineBasicBlock *New,
+                      bool NormalizeSuccProbs = false);
+
+  /// Transfers all the successors from MBB to this machine basic block (i.e.,
+  /// copies all the successors FromMBB and remove all the successors from
+  /// FromMBB).
+  void transferSuccessors(MachineBasicBlock *FromMBB);
+
+  /// Transfers all the successors, as in transferSuccessors, and update PHI
+  /// operands in the successor blocks which refer to FromMBB to refer to this.
+  void transferSuccessorsAndUpdatePHIs(MachineBasicBlock *FromMBB);
+
+  /// Return true if any of the successors have probabilities attached to them.
+  bool hasSuccessorProbabilities() const { return !Probs.empty(); }
+
+  /// Return true if the specified MBB is a predecessor of this block.
+  bool isPredecessor(const MachineBasicBlock *MBB) const;
+
+  /// Return true if the specified MBB is a successor of this block.
+  bool isSuccessor(const MachineBasicBlock *MBB) const;
+
+  /// Return true if the specified MBB will be emitted immediately after this
+  /// block, such that if this block exits by falling through, control will
+  /// transfer to the specified MBB. Note that MBB need not be a successor at
+  /// all, for example if this block ends with an unconditional branch to some
+  /// other block.
+  bool isLayoutSuccessor(const MachineBasicBlock *MBB) const;
+
+  /// Return the fallthrough block if the block can implicitly
+  /// transfer control to the block after it by falling off the end of
+  /// it.  This should return null if it can reach the block after
+  /// it, but it uses an explicit branch to do so (e.g., a table
+  /// jump).  Non-null return  is a conservative answer.
+  MachineBasicBlock *getFallThrough();
+
+  /// Return true if the block can implicitly transfer control to the
+  /// block after it by falling off the end of it.  This should return
+  /// false if it can reach the block after it, but it uses an
+  /// explicit branch to do so (e.g., a table jump).  True is a
+  /// conservative answer.
+  bool canFallThrough();
+
+  /// Returns a pointer to the first instruction in this block that is not a
+  /// PHINode instruction. When adding instructions to the beginning of the
+  /// basic block, they should be added before the returned value, not before
+  /// the first instruction, which might be PHI.
+  /// Returns end() is there's no non-PHI instruction.
+  iterator getFirstNonPHI();
+
+  /// Return the first instruction in MBB after I that is not a PHI or a label.
+  /// This is the correct point to insert lowered copies at the beginning of a
+  /// basic block that must be before any debugging information.
+  iterator SkipPHIsAndLabels(iterator I);
+
+  /// Return the first instruction in MBB after I that is not a PHI, label or
+  /// debug.  This is the correct point to insert copies at the beginning of a
+  /// basic block.
+  iterator SkipPHIsLabelsAndDebug(iterator I);
+
+  /// Returns an iterator to the first terminator instruction of this basic
+  /// block. If a terminator does not exist, it returns end().
+  iterator getFirstTerminator();
+  const_iterator getFirstTerminator() const {
+    return const_cast<MachineBasicBlock *>(this)->getFirstTerminator();
+  }
+
+  /// Same getFirstTerminator but it ignores bundles and return an
+  /// instr_iterator instead.
+  instr_iterator getFirstInstrTerminator();
+
+  /// Returns an iterator to the first non-debug instruction in the basic block,
+  /// or end().
+  iterator getFirstNonDebugInstr();
+  const_iterator getFirstNonDebugInstr() const {
+    return const_cast<MachineBasicBlock *>(this)->getFirstNonDebugInstr();
+  }
+
+  /// Returns an iterator to the last non-debug instruction in the basic block,
+  /// or end().
+  iterator getLastNonDebugInstr();
+  const_iterator getLastNonDebugInstr() const {
+    return const_cast<MachineBasicBlock *>(this)->getLastNonDebugInstr();
+  }
+
+  /// Convenience function that returns true if the block ends in a return
+  /// instruction.
+  bool isReturnBlock() const {
+    return !empty() && back().isReturn();
+  }
+
+  /// Convenience function that returns true if the bock ends in a EH scope
+  /// return instruction.
+  bool isEHScopeReturnBlock() const {
+    return !empty() && back().isEHScopeReturn();
+  }
+
+  /// Split a basic block into 2 pieces at \p SplitPoint. A new block will be
+  /// inserted after this block, and all instructions after \p SplitInst moved
+  /// to it (\p SplitInst will be in the original block). If \p LIS is provided,
+  /// LiveIntervals will be appropriately updated. \return the newly inserted
+  /// block.
+  ///
+  /// If \p UpdateLiveIns is true, this will ensure the live ins list is
+  /// accurate, including for physreg uses/defs in the original block.
+  MachineBasicBlock *splitAt(MachineInstr &SplitInst, bool UpdateLiveIns = true,
+                             LiveIntervals *LIS = nullptr);
+
+  /// Split the critical edge from this block to the given successor block, and
+  /// return the newly created block, or null if splitting is not possible.
+  ///
+  /// This function updates LiveVariables, MachineDominatorTree, and
+  /// MachineLoopInfo, as applicable.
+  MachineBasicBlock *
+  SplitCriticalEdge(MachineBasicBlock *Succ, Pass &P,
+                    std::vector<SparseBitVector<>> *LiveInSets = nullptr);
+
+  /// Check if the edge between this block and the given successor \p
+  /// Succ, can be split. If this returns true a subsequent call to
+  /// SplitCriticalEdge is guaranteed to return a valid basic block if
+  /// no changes occurred in the meantime.
+  bool canSplitCriticalEdge(const MachineBasicBlock *Succ) const;
+
+  void pop_front() { Insts.pop_front(); }
+  void pop_back() { Insts.pop_back(); }
+  void push_back(MachineInstr *MI) { Insts.push_back(MI); }
+
+  /// Insert MI into the instruction list before I, possibly inside a bundle.
+  ///
+  /// If the insertion point is inside a bundle, MI will be added to the bundle,
+  /// otherwise MI will not be added to any bundle. That means this function
+  /// alone can't be used to prepend or append instructions to bundles. See
+  /// MIBundleBuilder::insert() for a more reliable way of doing that.
+  instr_iterator insert(instr_iterator I, MachineInstr *M);
+
+  /// Insert a range of instructions into the instruction list before I.
+  template<typename IT>
+  void insert(iterator I, IT S, IT E) {
+    assert((I == end() || I->getParent() == this) &&
+           "iterator points outside of basic block");
+    Insts.insert(I.getInstrIterator(), S, E);
+  }
+
+  /// Insert MI into the instruction list before I.
+  iterator insert(iterator I, MachineInstr *MI) {
+    assert((I == end() || I->getParent() == this) &&
+           "iterator points outside of basic block");
+    assert(!MI->isBundledWithPred() && !MI->isBundledWithSucc() &&
+           "Cannot insert instruction with bundle flags");
+    return Insts.insert(I.getInstrIterator(), MI);
+  }
+
+  /// Insert MI into the instruction list after I.
+  iterator insertAfter(iterator I, MachineInstr *MI) {
+    assert((I == end() || I->getParent() == this) &&
+           "iterator points outside of basic block");
+    assert(!MI->isBundledWithPred() && !MI->isBundledWithSucc() &&
+           "Cannot insert instruction with bundle flags");
+    return Insts.insertAfter(I.getInstrIterator(), MI);
+  }
+
+  /// If I is bundled then insert MI into the instruction list after the end of
+  /// the bundle, otherwise insert MI immediately after I.
+  instr_iterator insertAfterBundle(instr_iterator I, MachineInstr *MI) {
+    assert((I == instr_end() || I->getParent() == this) &&
+           "iterator points outside of basic block");
+    assert(!MI->isBundledWithPred() && !MI->isBundledWithSucc() &&
+           "Cannot insert instruction with bundle flags");
+    while (I->isBundledWithSucc())
+      ++I;
+    return Insts.insertAfter(I, MI);
+  }
+
+  /// Remove an instruction from the instruction list and delete it.
+  ///
+  /// If the instruction is part of a bundle, the other instructions in the
+  /// bundle will still be bundled after removing the single instruction.
+  instr_iterator erase(instr_iterator I);
+
+  /// Remove an instruction from the instruction list and delete it.
+  ///
+  /// If the instruction is part of a bundle, the other instructions in the
+  /// bundle will still be bundled after removing the single instruction.
+  instr_iterator erase_instr(MachineInstr *I) {
+    return erase(instr_iterator(I));
+  }
+
+  /// Remove a range of instructions from the instruction list and delete them.
+  iterator erase(iterator I, iterator E) {
+    return Insts.erase(I.getInstrIterator(), E.getInstrIterator());
+  }
+
+  /// Remove an instruction or bundle from the instruction list and delete it.
+  ///
+  /// If I points to a bundle of instructions, they are all erased.
+  iterator erase(iterator I) {
+    return erase(I, std::next(I));
+  }
+
+  /// Remove an instruction from the instruction list and delete it.
+  ///
+  /// If I is the head of a bundle of instructions, the whole bundle will be
+  /// erased.
+  iterator erase(MachineInstr *I) {
+    return erase(iterator(I));
+  }
+
+  /// Remove the unbundled instruction from the instruction list without
+  /// deleting it.
+  ///
+  /// This function can not be used to remove bundled instructions, use
+  /// remove_instr to remove individual instructions from a bundle.
+  MachineInstr *remove(MachineInstr *I) {
+    assert(!I->isBundled() && "Cannot remove bundled instructions");
+    return Insts.remove(instr_iterator(I));
+  }
+
+  /// Remove the possibly bundled instruction from the instruction list
+  /// without deleting it.
+  ///
+  /// If the instruction is part of a bundle, the other instructions in the
+  /// bundle will still be bundled after removing the single instruction.
+  MachineInstr *remove_instr(MachineInstr *I);
+
+  void clear() {
+    Insts.clear();
+  }
+
+  /// Take an instruction from MBB 'Other' at the position From, and insert it
+  /// into this MBB right before 'Where'.
+  ///
+  /// If From points to a bundle of instructions, the whole bundle is moved.
+  void splice(iterator Where, MachineBasicBlock *Other, iterator From) {
+    // The range splice() doesn't allow noop moves, but this one does.
+    if (Where != From)
+      splice(Where, Other, From, std::next(From));
+  }
+
+  /// Take a block of instructions from MBB 'Other' in the range [From, To),
+  /// and insert them into this MBB right before 'Where'.
+  ///
+  /// The instruction at 'Where' must not be included in the range of
+  /// instructions to move.
+  void splice(iterator Where, MachineBasicBlock *Other,
+              iterator From, iterator To) {
+    Insts.splice(Where.getInstrIterator(), Other->Insts,
+                 From.getInstrIterator(), To.getInstrIterator());
+  }
+
+  /// This method unlinks 'this' from the containing function, and returns it,
+  /// but does not delete it.
+  MachineBasicBlock *removeFromParent();
+
+  /// This method unlinks 'this' from the containing function and deletes it.
+  void eraseFromParent();
+
+  /// Given a machine basic block that branched to 'Old', change the code and
+  /// CFG so that it branches to 'New' instead.
+  void ReplaceUsesOfBlockWith(MachineBasicBlock *Old, MachineBasicBlock *New);
+
+  /// Update all phi nodes in this basic block to refer to basic block \p New
+  /// instead of basic block \p Old.
+  void replacePhiUsesWith(MachineBasicBlock *Old, MachineBasicBlock *New);
+
+  /// Find the next valid DebugLoc starting at MBBI, skipping any DBG_VALUE
+  /// and DBG_LABEL instructions.  Return UnknownLoc if there is none.
+  DebugLoc findDebugLoc(instr_iterator MBBI);
+  DebugLoc findDebugLoc(iterator MBBI) {
+    return findDebugLoc(MBBI.getInstrIterator());
+  }
+
+  /// Find the previous valid DebugLoc preceding MBBI, skipping and DBG_VALUE
+  /// instructions.  Return UnknownLoc if there is none.
+  DebugLoc findPrevDebugLoc(instr_iterator MBBI);
+  DebugLoc findPrevDebugLoc(iterator MBBI) {
+    return findPrevDebugLoc(MBBI.getInstrIterator());
+  }
+
+  /// Find and return the merged DebugLoc of the branch instructions of the
+  /// block. Return UnknownLoc if there is none.
+  DebugLoc findBranchDebugLoc();
+
+  /// Possible outcome of a register liveness query to computeRegisterLiveness()
+  enum LivenessQueryResult {
+    LQR_Live,   ///< Register is known to be (at least partially) live.
+    LQR_Dead,   ///< Register is known to be fully dead.
+    LQR_Unknown ///< Register liveness not decidable from local neighborhood.
+  };
+
+  /// Return whether (physical) register \p Reg has been defined and not
+  /// killed as of just before \p Before.
+  ///
+  /// Search is localised to a neighborhood of \p Neighborhood instructions
+  /// before (searching for defs or kills) and \p Neighborhood instructions
+  /// after (searching just for defs) \p Before.
+  ///
+  /// \p Reg must be a physical register.
+  LivenessQueryResult computeRegisterLiveness(const TargetRegisterInfo *TRI,
+                                              MCRegister Reg,
+                                              const_iterator Before,
+                                              unsigned Neighborhood = 10) const;
+
+  // Debugging methods.
+  void dump() const;
+  void print(raw_ostream &OS, const SlotIndexes * = nullptr,
+             bool IsStandalone = true) const;
+  void print(raw_ostream &OS, ModuleSlotTracker &MST,
+             const SlotIndexes * = nullptr, bool IsStandalone = true) const;
+
+  enum PrintNameFlag {
+    PrintNameIr = (1 << 0), ///< Add IR name where available
+    PrintNameAttributes = (1 << 1), ///< Print attributes
+  };
+
+  void printName(raw_ostream &os, unsigned printNameFlags = PrintNameIr,
+                 ModuleSlotTracker *moduleSlotTracker = nullptr) const;
+
+  // Printing method used by LoopInfo.
+  void printAsOperand(raw_ostream &OS, bool PrintType = true) const;
+
+  /// MachineBasicBlocks are uniquely numbered at the function level, unless
+  /// they're not in a MachineFunction yet, in which case this will return -1.
+  int getNumber() const { return Number; }
+  void setNumber(int N) { Number = N; }
+
+  /// Return the MCSymbol for this basic block.
+  MCSymbol *getSymbol() const;
+
+  Optional<uint64_t> getIrrLoopHeaderWeight() const {
+    return IrrLoopHeaderWeight;
+  }
+
+  void setIrrLoopHeaderWeight(uint64_t Weight) {
+    IrrLoopHeaderWeight = Weight;
+  }
+
+private:
+  /// Return probability iterator corresponding to the I successor iterator.
+  probability_iterator getProbabilityIterator(succ_iterator I);
+  const_probability_iterator
+  getProbabilityIterator(const_succ_iterator I) const;
+
+  friend class MachineBranchProbabilityInfo;
+  friend class MIPrinter;
+
+  /// Return probability of the edge from this block to MBB. This method should
+  /// NOT be called directly, but by using getEdgeProbability method from
+  /// MachineBranchProbabilityInfo class.
+  BranchProbability getSuccProbability(const_succ_iterator Succ) const;
+
+  // Methods used to maintain doubly linked list of blocks...
+  friend struct ilist_callback_traits<MachineBasicBlock>;
+
+  // Machine-CFG mutators
+
+  /// Add Pred as a predecessor of this MachineBasicBlock. Don't do this
+  /// unless you know what you're doing, because it doesn't update Pred's
+  /// successors list. Use Pred->addSuccessor instead.
+  void addPredecessor(MachineBasicBlock *Pred);
+
+  /// Remove Pred as a predecessor of this MachineBasicBlock. Don't do this
+  /// unless you know what you're doing, because it doesn't update Pred's
+  /// successors list. Use Pred->removeSuccessor instead.
+  void removePredecessor(MachineBasicBlock *Pred);
+};
+
+raw_ostream& operator<<(raw_ostream &OS, const MachineBasicBlock &MBB);
+
+/// Prints a machine basic block reference.
+///
+/// The format is:
+///   %bb.5           - a machine basic block with MBB.getNumber() == 5.
+///
+/// Usage: OS << printMBBReference(MBB) << '\n';
+Printable printMBBReference(const MachineBasicBlock &MBB);
+
+// This is useful when building IndexedMaps keyed on basic block pointers.
+struct MBB2NumberFunctor {
+  using argument_type = const MachineBasicBlock *;
+  unsigned operator()(const MachineBasicBlock *MBB) const {
+    return MBB->getNumber();
+  }
+};
+
+//===--------------------------------------------------------------------===//
+// GraphTraits specializations for machine basic block graphs (machine-CFGs)
+//===--------------------------------------------------------------------===//
+
+// Provide specializations of GraphTraits to be able to treat a
+// MachineFunction as a graph of MachineBasicBlocks.
+//
+
+template <> struct GraphTraits<MachineBasicBlock *> {
+  using NodeRef = MachineBasicBlock *;
+  using ChildIteratorType = MachineBasicBlock::succ_iterator;
+
+  static NodeRef getEntryNode(MachineBasicBlock *BB) { return BB; }
+  static ChildIteratorType child_begin(NodeRef N) { return N->succ_begin(); }
+  static ChildIteratorType child_end(NodeRef N) { return N->succ_end(); }
+};
+
+template <> struct GraphTraits<const MachineBasicBlock *> {
+  using NodeRef = const MachineBasicBlock *;
+  using ChildIteratorType = MachineBasicBlock::const_succ_iterator;
+
+  static NodeRef getEntryNode(const MachineBasicBlock *BB) { return BB; }
+  static ChildIteratorType child_begin(NodeRef N) { return N->succ_begin(); }
+  static ChildIteratorType child_end(NodeRef N) { return N->succ_end(); }
+};
+
+// Provide specializations of GraphTraits to be able to treat a
+// MachineFunction as a graph of MachineBasicBlocks and to walk it
+// in inverse order.  Inverse order for a function is considered
+// to be when traversing the predecessor edges of a MBB
+// instead of the successor edges.
+//
+template <> struct GraphTraits<Inverse<MachineBasicBlock*>> {
+  using NodeRef = MachineBasicBlock *;
+  using ChildIteratorType = MachineBasicBlock::pred_iterator;
+
+  static NodeRef getEntryNode(Inverse<MachineBasicBlock *> G) {
+    return G.Graph;
+  }
+
+  static ChildIteratorType child_begin(NodeRef N) { return N->pred_begin(); }
+  static ChildIteratorType child_end(NodeRef N) { return N->pred_end(); }
+};
+
+template <> struct GraphTraits<Inverse<const MachineBasicBlock*>> {
+  using NodeRef = const MachineBasicBlock *;
+  using ChildIteratorType = MachineBasicBlock::const_pred_iterator;
+
+  static NodeRef getEntryNode(Inverse<const MachineBasicBlock *> G) {
+    return G.Graph;
+  }
+
+  static ChildIteratorType child_begin(NodeRef N) { return N->pred_begin(); }
+  static ChildIteratorType child_end(NodeRef N) { return N->pred_end(); }
+};
+
+/// MachineInstrSpan provides an interface to get an iteration range
+/// containing the instruction it was initialized with, along with all
+/// those instructions inserted prior to or following that instruction
+/// at some point after the MachineInstrSpan is constructed.
+class MachineInstrSpan {
+  MachineBasicBlock &MBB;
+  MachineBasicBlock::iterator I, B, E;
+
+public:
+  MachineInstrSpan(MachineBasicBlock::iterator I, MachineBasicBlock *BB)
+      : MBB(*BB), I(I), B(I == MBB.begin() ? MBB.end() : std::prev(I)),
+        E(std::next(I)) {
+    assert(I == BB->end() || I->getParent() == BB);
+  }
+
+  MachineBasicBlock::iterator begin() {
+    return B == MBB.end() ? MBB.begin() : std::next(B);
+  }
+  MachineBasicBlock::iterator end() { return E; }
+  bool empty() { return begin() == end(); }
+
+  MachineBasicBlock::iterator getInitial() { return I; }
+};
+
+/// Increment \p It until it points to a non-debug instruction or to \p End
+/// and return the resulting iterator. This function should only be used
+/// MachineBasicBlock::{iterator, const_iterator, instr_iterator,
+/// const_instr_iterator} and the respective reverse iterators.
+template<typename IterT>
+inline IterT skipDebugInstructionsForward(IterT It, IterT End) {
+  while (It != End && It->isDebugInstr())
+    ++It;
+  return It;
+}
+
+/// Decrement \p It until it points to a non-debug instruction or to \p Begin
+/// and return the resulting iterator. This function should only be used
+/// MachineBasicBlock::{iterator, const_iterator, instr_iterator,
+/// const_instr_iterator} and the respective reverse iterators.
+template<class IterT>
+inline IterT skipDebugInstructionsBackward(IterT It, IterT Begin) {
+  while (It != Begin && It->isDebugInstr())
+    --It;
+  return It;
+}
+
+/// Increment \p It, then continue incrementing it while it points to a debug
+/// instruction. A replacement for std::next.
+template <typename IterT> inline IterT next_nodbg(IterT It, IterT End) {
+  return skipDebugInstructionsForward(std::next(It), End);
+}
+
+/// Decrement \p It, then continue decrementing it while it points to a debug
+/// instruction. A replacement for std::prev.
+template <typename IterT> inline IterT prev_nodbg(IterT It, IterT Begin) {
+  return skipDebugInstructionsBackward(std::prev(It), Begin);
+}
+
+/// Construct a range iterator which begins at \p It and moves forwards until
+/// \p End is reached, skipping any debug instructions.
+template <typename IterT>
+inline auto instructionsWithoutDebug(IterT It, IterT End) {
+  return make_filter_range(make_range(It, End), [](const MachineInstr &MI) {
+    return !MI.isDebugInstr();
+  });
+}
+
+} // end namespace llvm
+
+#endif // LLVM_CODEGEN_MACHINEBASICBLOCK_H
+
+#ifdef __GNUC__
+#pragma GCC diagnostic pop
+#endif